The early history of comets can be divided into five major periods, each one being noted by important new observations. The word comet comes from Greek kometes which means "the hairy one", and is used in all European languages today. The earliest records of comet observatory can be dated as far back as 1000 China and around the same time in Chaldea (present-day Iraq). The first actual ideas of comets happened around the Hellenistic natural philosophy era (-550). The Pythagoreans believed that comets were wandering planets that were hardly ever seen and mainly seen near the horizon in the morning or evening sky. Aristotle described comets as dry and warm exhalations in the upper atmosphere. However, before the 1600s comets were usually considered to be heavenly evil omens, until finally in 1456 Paolo Tascanelli observed Haley’s comet and other comets around 1433 and 1472. The era of cometary physics, although, was not added to astronomy till about the 19th century. This critical demonstration was delivered by Tycho Brahe, he observed a bright comet which first appeared in late 1577.
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FORMATION
Comets are the left overs of the solar systems formation (solar nebula) about 4.56 billion years ago. They were once believed to be a collection of sand and pebbles that formed floating throughout space. We now know that a comet is more of a dirty snowball of ice and dust that releases gas or dust. They also contain a lot of carbon rich materials, comets are also believed to contain to building blocks of life. Scientists believe that the speed it takes for comets to form would have depended on the size of the solar nebula. Another theory is that there was once a planet between Mars and Jupiter and Jupiter's gravity pulled it apart leaving the asteroid belt and what fragmented and became frozen in space was part of that planets atmosphere and it began to orbit the sun, throwing it out further and further.
LOCATIONS
Comets are believed to exist in great numbers in a distant shell around the Sun called the Oort cloud. Because some are rather large, and the fact that collisions or near encounters occur in the cloud, comets sometimes get dislodged from their stable, distant orbits. When this happens, they end up in highly elliptical orbits that take them near the sun. When comets come close enough to the Sun, the frozen water begins to melt and turn into vapor. The vapor and dust on the comet become dislodged and become visible as a tail on the comet. Every 10 years or so a comet becomes easily visible to the naked eye, and grabs enormous interest.
PARTS OF A COMET
A comet consists of five parts; Nucleus, coma, hydrogen envelope, dust tail and the ion tail. The main part of the comet is the nucleus, the solid part of the comet. Its size is usually from 1 to 10 kilometers in diameter but can be as big as 100 kilometers. The comet consists a halo of gases and dust surrounding the nucleus, being released as it gets closer to the sun. Ammonia, carbon dioxide, and water vapor are the the gases being released. The coma and the nucleus create the head of a comet. Most of all comets come from the Kuniper belt between Uranus and Neptune. As well as the Oort Cloud which is beyond Pluto. Comets will always be remembered for there streaks of light they leave in the sky.
picture courtesy of kendalastronomer.wordpress.com
Table of Contents
Comets
The early history of comets can be divided into five major periods, each one being noted by important new observations. The word comet comes from Greek kometes which means "the hairy one", and is used in all European languages today. The earliest records of comet observatory can be dated as far back as 1000 China and around the same time in Chaldea (present-day Iraq). The first actual ideas of comets happened around the Hellenistic natural philosophy era (-550). The Pythagoreans believed that comets were wandering planets that were hardly ever seen and mainly seen near the horizon in the morning or evening sky. Aristotle described comets as dry and warm exhalations in the upper atmosphere. However, before the 1600s comets were usually considered to be heavenly evil omens, until finally in 1456 Paolo Tascanelli observed Haley’s comet and other comets around 1433 and 1472. The era of cometary physics, although, was not added to astronomy till about the 19th century. This critical demonstration was delivered by Tycho Brahe, he observed a bright comet which first appeared in late 1577.FORMATION
Comets are the left overs of the solar systems formation (solar nebula) about 4.56 billion years ago. They were once believed to be a collection of sand and pebbles that formed floating throughout space. We now know that a comet is more of a dirty snowball of ice and dust that releases gas or dust. They also contain a lot of carbon rich materials, comets are also believed to contain to building blocks of life. Scientists believe that the speed it takes for comets to form would have depended on the size of the solar nebula. Another theory is that there was once a planet between Mars and Jupiter and Jupiter's gravity pulled it apart leaving the asteroid belt and what fragmented and became frozen in space was part of that planets atmosphere and it began to orbit the sun, throwing it out further and further.
LOCATIONS
Comets are believed to exist in great numbers in a distant shell around the Sun called the Oort cloud. Because some are rather large, and the fact that collisions or near encounters occur in the cloud, comets sometimes get dislodged from their stable, distant orbits. When this happens, they end up in highly elliptical orbits that take them near the sun. When comets come close enough to the Sun, the frozen water begins to melt and turn into vapor. The vapor and dust on the comet become dislodged and become visible as a tail on the comet. Every 10 years or so a comet becomes easily visible to the naked eye, and grabs enormous interest.
PARTS OF A COMET
A comet consists of five parts; Nucleus, coma, hydrogen envelope, dust tail and the ion tail. The main part of the comet is the nucleus, the solid part of the comet. Its size is usually from 1 to 10 kilometers in diameter but can be as big as 100 kilometers. The comet consists a halo of gases and dust surrounding the nucleus, being released as it gets closer to the sun. Ammonia, carbon dioxide, and water vapor are the the gases being released. The coma and the nucleus create the head of a comet. Most of all comets come from the Kuniper belt between Uranus and Neptune. As well as the Oort Cloud which is beyond Pluto. Comets will always be remembered for there streaks of light they leave in the sky.
REFERENCES